Answer:
Ne
Explanation:
Atomic number of Ne is 10.
Electronic configuration of Ne:
[tex]1s^2 2s^2 2p^6[/tex]
Octet of Ne is complete . Element having complete octet are stable and behave ideal gas.
[tex]N_2[/tex] and [tex]CH_4[/tex] are reactive and hence, does not behave as ideal gas.